1.Field of the Invention
The field of art to which this invention pertains is fluid reaction surfaces with cooling means utilizing fluid flow through the working member.
2. Description of the Prior Art
Various means have been used to cool rotating heat exchangers such as used with turbine blades by passing liquid coolant through the blade. For example, U.S. Pat. No. 4,118,145 uses a channeled blade wherein the coolant is projected against a collection surface and the coolant is passed through the blade from the collection surface by virtue of centrifugal force. However, no means are disclosed in such system for metering or controlling the amount of flow into and out of the blade or for attaining the supercritical pressures and temperatures desired. Similarly, U.S. Pat. No. 2,647,368 describes a system of projecting coolant against a collection surface which is subsequently forced through the turbine blade by centrifugal force. Again, there are no provisions in this latter patent for metering or controlling both the inlet and exhaust of the coolant to take into account variances from blade to blade from a central coolant source to provide such things as supercritical pressures and temperatures in the system.
It has also been proposed to use a single orifice coolant control system for turbine blades (e.g., U.S. Pat. No. 3,902,819). The primary problem with such systems is that it is difficult to reach the desired situation in the turbine blade where the coolant is present in the turbine engine assembly and in the blades in particular at supercritical temperature and pressure. For a flow control system with a pressure controlled inlet and a single orifice at the outlet the coolant discharge would not reach supercritical temperatures and the flow rate would be five times what is necessary to cool the blade with supercritical temperatures for the coolant discharge. With the present invention, much greater control can be exercised in coolant flow rates resulting in the attainment and maintenance of supercritical temperatures and pressures at the coolant discharge location with minimal time lag.
Accordingly, the present invention provides an engine assembly with a flow control system for use with fluid cooled turbine blades, and especially water cooled turbine blades, which provides metering inlet and outlet orifices in the turbine disc, thereby achieving supercritical temperature and pressure of the coolant in the blades.